CN104506106A - Excitation control and zero-speed start method for doubly-fed motors - Google Patents

Abstract

The invention relates to an excitation control and zero-speed start method for doubly-fed motors. The excitation control and zero-speed start method includes carrying out 2r/2s conversion on control voltages of rotor shafts d and q to obtain control required rotor voltages in a two-phase stationary coordinate system alpha-beta; providing the rotor voltages to a SVPWM (space vector pulse width modulation) module; generating trigger pulses by the aid of a voltage SVPWM algorithm to drive an inverter to excite a rotor; indirectly enabling a stator winding to absorb reactive power from power grids and exciting a stator so as to control excitation and zero-speed load-carrying start of the doubly-fed motors. The rotor voltages which are provided to the SVPWM module are used as reference voltages. The excitation control and zero-speed start method has the advantages that the problem of excessively high cost input due to excessively high terminal voltages of rotor windings of doubly-fed motors, high selected voltage values of direct-current buses and required high-power devices when the doubly-fed motors are started at zero speed by the aid of excitation regulation on rotors can be solved by the aid of the excitation control and zero-speed start method; problems of jittering and instability of rotation speeds and output torque when the traditional PI (proportional-integral) regulators are used as zero-speed controllers can be solved by the aid of the excitation control and zero-speed start method.

Description

A kind of double feedback electric engine excitation con-trol and zero-speed starting method

Technical field

The present invention relates to a kind of control and starting method of double feedback electric engine, particularly relate to a kind of double feedback electric engine excitation con-trol and zero-speed starting method, belong to double feedback electric engine Drag Control field.

Background technology

Along with the development of power electronic technology and Theory of Automatic Control, adopt the doubly-fed control system of high-power converter and double feedback electric engine composition to receive to pay close attention to widely, be specially adapted to alternating current machine drag and the field such as governing system, speed-varying frequency constant dual feedback wind power generation system, possessed that power factor is adjustable, efficiency comparatively high energy advantage.In doubly-fed adjustable speed system, double feedback electric engine stator winding is connected with three-phase main-frequency electrical network, and rotor windings is connected with power supply through current transformer, by the control controlling the amplitude of rotor windings voltage and electric current, phase place, frequency realize double feedback electric engine.Because double feedback electric engine realizes above-mentioned control by rotor-side converter, therefore the power of rotor-side converter process is slip power.And when double feedback electric engine zero-speed starts, the slip angular velocity of double feedback electric engine equals angular stator frequency, corresponding slip power is double feedback electric engine total power, now rotor windings terminal voltage is the highest, need current transformer to adopt the device for power switching of higher DC bus-bar voltage and high voltage grade, add equipment cost and drop into.

Meanwhile, under zero-speed condition, when doubly-fed control system promotes potential load for dragging, double feedback electric engine is needed to provide the electromagnetic torque contrary with load in short-term.Traditional control method is given motor speed is zero, gathers the feedback signal of motor speed, and both deviations export the torque current signal needed for controlling through pi regulator.In order to ensure good zero-speed startability, need to increase d-c bus voltage value to keep rotating speed and the less jitter value of electromagnetic torque amount, thus cause the device for power switching needing employing high voltage grade, expand Converter Capacity further, add cost and drop into.

In addition, adopt traditional PI adjuster as zero-speed controller, double feedback electric engine running speed close to zero-speed and even zero-speed time, export electromagnetic torque discontinuous situation under, proportion adjustment ring P in pi regulator is inoperative, now, be only that integral adjustment ring I in pi regulator is playing a role, the stability requirement that zero-speed starts under global conditions can not be met.Therefore be necessary to be improved solution to the problems referred to above.

Summary of the invention

The present invention, just for the technical problem existed in prior art, provides a kind of double feedback electric engine excitation con-trol and zero-speed starting method, the method operating cost is low, zero-speed starts and stablizes, is easy to realize under global conditions.

To achieve these goals, the technical solution used in the present invention is, a kind of double feedback electric engine excitation con-trol and zero-speed starting method, comprise the following steps:

(1) gather threephase stator winding voltage and current signal, determine stator magnetic linkage amplitude and stator magnet chain angle;

(2) by stator magnetic linkage and mutual inductance parameter, the specified rate of single rotor excitation condition lower rotor part current excitation component is calculated:

(3) set-point defining rotor excitation current is the specified rate of Stator energization current component and the specified rate sum of rotor excitation current component, calculate limit lower rotor part electric current d axle component, under Guarantee control system stable case, obtain the given higher limit of rotor excitation current;

(4) picking rate feedback signal, carries out initial torque current observation to double feedback electric engine, calculates initial torque current set-point;

(5) realize rotor current closed-loop control based on pi regulator, adopt feedforward compensation strategy, making rotor current inner ring realize uneoupled control, meanwhile, is simple first order inertial loop relation by the Relationship Change of rotor-end voltage and rotor current;

(6) rotor d, q axle control voltage is converted through 2r/2s, obtain the rotor voltage needed for control under two-phase static α β coordinate system, this voltage is supplied to SVPWM module as the reference voltage, adopting Voltage space vector PWM (SVPWM) modulation algorithm to generate trigger impulse drives inverter to be rotor-exciting, indirectly make stator winding carry out stator excitation from electrical network absorption is idle, thus realization carry startup control to the excitation con-trol of double feedback electric engine and zero-speed band.

Further, step (1) is eliminate the impact of initial value for integral and the DC component adopting pure integrator to bring, and adopt three low-pass first order filter cascades to build stator flux observer, its corresponding transfer function is:

$G\left(s\right)=\frac{2\·\sqrt[3]{{\mathrm{\ω}}_c^2}}{s+\sqrt{3}{\mathrm{\ω}}_c}\·\frac{2\·\sqrt[3]{{\mathrm{\ω}}_c^2}}{s+\sqrt{3}{\mathrm{\ω}}_c}\·\frac{2\·\sqrt[3]{{\mathrm{\ω}}_c^2}}{s+\sqrt{3}{\mathrm{\ω}}_c}$

Further, step (3) calculates limit lower rotor part electric current d axle component, introduces double feedback electric engine stator voltage vector u _swith the angle theta of dq coordinate system d axle _u, its computing formula is:

$i_{\mathrm{rd}}=\frac{L_s}{R_s{L}_m}(\frac{R_s}{L_s}{\mathrm{\ψ}}_s-u_s\cos {\mathrm{\θ}}_u)$

In formula: R _sfor double feedback electric engine stator resistance; ψ _sfor stator magnetic linkage amplitude; L _mfor winding equivalence mutual inductance under dq coordinate system; L _sfor stator winding equivalent self inductance.

Further, step (5) detailed process is as follows:

A) corresponding relation of rotor-end voltage and rotor current is determined:

$\left\{\begin{array}{c}{u}_{\mathrm{rd}}=R_r{i}_{\mathrm{rd}}+(L_r-\frac{L_m^2}{L_s}){\mathrm{pi}}_{\mathrm{rd}}-{\mathrm{\ω}}_s(L_r-\frac{L_m^2}{L_s})i_{\mathrm{rq}}\\ u_{\mathrm{rq}}=R_r{i}_{\mathrm{rq}}+(L_r-\frac{L_m^2}{L_s}){\mathrm{pi}}_{\mathrm{rq}}+{\mathrm{\ω}}_s(L_r-\frac{L_m^2}{L_s})i_{\mathrm{rd}}+{\mathrm{\ω}}_s\frac{L_m}{L_s}{\mathrm{\ψ}}_{\mathrm{sd}}\end{array}\right.$

B) adopt pi regulator as the controller of inner ring electric current loop, it exports the control as rotor current dynamic item, and its governing equation is as follows:

$\left\{\begin{array}{c}{u}_{\mathrm{rd}}=(k_p+\frac{k_i}{s})(i_{\mathrm{rd}}^{*}-i_{\mathrm{rd}})-{\mathrm{\ω}}_s(L_r-\frac{L_m^2}{L_s})i_{\mathrm{rq}}\\ u_{\mathrm{rq}}=(k_p+\frac{k_i}{s})(i_{\mathrm{rq}}^{*}-i_{\mathrm{rq}})+{\mathrm{\ω}}_s(L_r-\frac{L_m^2}{L_s})i_{\mathrm{rd}}+{\mathrm{\ω}}_s\frac{L_m}{L_s}{\mathrm{\ψ}}_{\mathrm{sd}}\end{array}\right.$

C) by the Relationship Change of rotor terminal voltage and rotor current be simple first order inertial loop relation such as formula shown:

$\begin{array}{c}\left[\begin{array}{c}{\mathrm{pi}}_{\mathrm{rd}}\\ {\mathrm{pi}}_{\mathrm{rq}}\end{array}\right]=\left[\begin{array}{cc}-\frac{L_s}{L_s{L}_r-L_m^2}[R_r+(k_p+\frac{k_i}{s})]& 0\\ 0& -\frac{L_s}{L_s{L}_r-L_m^2}[R_r+(k_p+\frac{k_i}{s})]\end{array}\right]\\ +(k_p+\frac{k_i}{s})\left[\begin{array}{c}{i}_{\mathrm{rd}}^{*}\\ i_{\mathrm{rq}}^{*}\end{array}\right]\end{array}\left[\begin{array}{c}{i}_{\mathrm{rd}}\\ i_{\mathrm{rq}}\end{array}\right]$

D) adopt feedforward compensation strategy, make double fed electric machine rotor current inner loop achieve uneoupled control.

Further, the method is applicable to current transformer power device electric pressure and DC bus-bar voltage and is less than and controls the occasion that double feedback electric engine starts the rotor voltage produced.

Compared with prior art, there is following beneficial effect in the present invention: the invention solves double feedback electric engine zero-speed and start the adjustment of employing rotor-exciting, double fed electric machine rotor winding terminal overtension, d-c bus voltage value is caused to choose the cost input problems of too needing high voltage power device to bring comparatively greatly, and when overcoming employing traditional PI adjuster as zero-speed controller, rotating speed and Driving Torque shake instability problem.

Accompanying drawing explanation

Fig. 1 double feedback electric engine excitation con-trol of the present invention and zero-speed starting method systematic schematic diagram;

Fig. 2 zero-speed band carries control imitation waveform;

Fig. 3 double feedback electric engine excitation con-trol zero-speed starts experimental waveform.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.

Fig. 1 is double feedback electric engine excitation con-trol of the present invention and zero-speed starting method systematic schematic diagram, and its device realizing the method is made up of DC power supply 1, DC bus Support Capacitor 2, inverter 3, SVPWM pulse-triggered 4, stator flux observer 5, zero-speed controller 6, torque current pi regulator 7, the given calculating 8 of exciting current, exciting current pi regulator 9, rotor feedforward compensation 10, trigger voltage Park inverse transformer 11, velocity transducer 12, rotor current 3s/2r converter 13, stator voltage 3s/2s converter 14, stator current 3s/2s converter 15.

By velocity transducer 12 picking rate feedback signal ω _rto zero-speed controller 6, the torque current signal set-point of zero-speed controller 6 output rotor electric current rotor current 3s/2r converter 13 output rotor current torque signal feedback value i _rq, the deviation of set-point and value of feedback is through torque current pi regulator 7 output rotor voltage signal d axle component u _rq; Stator flux observer 5 gathers stator winding voltage, current signal calculates stator magnetic linkage amplitude ψ _sand stator magnetic linkage oriented angle θ _s, be supplied to rotor feedforward compensation 10 respectively and for angle of transformation needed for rotor current 3s/2r converter 13; Exciting current given calculating 8 output rotor exciting current Setting signal rotor current 3s/2r converter 13 output rotor exciting current signal feedback value i _rd, the deviation of set-point and value of feedback is through exciting current pi regulator 9 output rotor voltage signal q axle component u _rd; Two-phase rotating coordinate system rotor voltage signal u _rd, u _rqcalculate link 10 output cross coupling terms in conjunction with decoupling zero item and realize Feedforward Decoupling, output rotor voltage control Setting signal the reference voltage signal u needed for control SVPWM pulse-triggered 4 is exported through trigger voltage Park inverse transformer 11 _{r α}, u _{r β}, SVPWM pulse-triggered 4 output triggering driving inverter is rotor-exciting, and from stator winding from electrical network, absorption is idle simultaneously carries out stator excitation, and then realization carries startup control to the excitation con-trol of double feedback electric engine and zero-speed band.

Implement a kind of double feedback electric engine excitation con-trol of the present invention and zero-speed starting method, specifically follow these steps to realize:

(1) gather threephase stator winding voltage and current signal, determine stator magnetic linkage amplitude and stator magnet chain angle;

During double feedback electric engine employing stator-flux-oriented vector control, the voltage model based on stator winding can obtain flux linkage model expression formula as shown in (1):

$\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{s\α}}=\∫(u_{\mathrm{s\α}}-R_s{i}_{\mathrm{s\α}})\mathrm{dt}\\ {\mathrm{\ψ}}_{\mathrm{s\β}}=\∫(u_{\mathrm{s\β}}-R_s{i}_{\mathrm{s\β}})\mathrm{dt}\end{array}\right.---\left(1\right)$

In two-phase rest frame, can obtain stator magnetic linkage amplitude and stator magnetic linkage oriented angle further, its basic calculating formula is:

$\left\{\begin{array}{c}\left|{\mathrm{\ψ}}_s\right|=\sqrt{{\mathrm{\ψ}}_{\mathrm{s\α}}^2+{\mathrm{\ψ}}_{\mathrm{s\β}}^2}\\ {\mathrm{\θ}}_s=\arctan {\mathrm{\ψ}}_{\mathrm{s\α}}/{\mathrm{\ψ}}_{\mathrm{s\β}}\end{array}\right.---\left(2\right)$

In formula: u _{s α}, u _{s β}the component of stator voltage at α, β axle respectively; i _{s α}, i _{s β}the component of stator current at α, β axle respectively; ψ _{s α}, ψ _{s β}the component of stator magnetic linkage at α, β axle respectively; R _sfor double feedback electric engine stator resistance; ψ _sfor stator magnetic linkage amplitude; θ _sfor stator magnet chain angle.

For eliminating the impact of initial value for integral and the DC component adopting pure integrator to bring, adopt three low-pass first order filter cascades to build stator flux observer, its corresponding transfer function is:

$G\left(s\right)=\frac{2\·\sqrt[3]{{\mathrm{\ω}}_c^2}}{s+\sqrt{3}{\mathrm{\ω}}_c}\·\frac{2\·\sqrt[3]{{\mathrm{\ω}}_c^2}}{s+\sqrt{3}{\mathrm{\ω}}_c}\·\frac{2\·\sqrt[3]{{\mathrm{\ω}}_c^2}}{s+\sqrt{3}{\mathrm{\ω}}_c}---\left(3\right)$

For this reason, stator magnetic linkage in two-phase rest frame can be obtained and stator magnet chain angle is:

$\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{s\α}}=G\left(s\right)\·(u_{\mathrm{s\α}}-R_s{i}_{\mathrm{s\α}})\\ {\mathrm{\ψ}}_{\mathrm{s\β}}=G\left(s\right)\·(u_{\mathrm{s\β}}-R_s{i}_{\mathrm{s\β}})\\ \left|{\mathrm{\ψ}}_s\right|=\sqrt{{\mathrm{\ψ}}_{\mathrm{s\α}}^2+{\mathrm{\ψ}}_{\mathrm{s\β}}^2}\\ {\mathrm{\θ}}_s=\arctan {\mathrm{\ψ}}_{\mathrm{s\α}}/{\mathrm{\ψ}}_{\mathrm{s\β}}\end{array}\right.---\left(4\right)$

(2) by stator magnetic linkage and mutual inductance parameter, the specified rate of single rotor excitation condition lower rotor part current excitation component is calculated; At two-phase synchronous rotary d, in q coordinate system, the current model of double feedback electric engine stator magnetic linkage is:

$\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{sd}}=L_s{i}_{\mathrm{sd}}+L_m{i}_{\mathrm{rd}}\\ {\mathrm{\ψ}}_{\mathrm{sq}}=L_s{i}_{\mathrm{sq}}+L_m{i}_{\mathrm{rq}}\end{array}\right.---\left(5\right)$

In formula: ψ _sd, ψ _sqthe component of stator and rotor magnetic linkage at d, q axle respectively; L _mfor winding equivalence mutual inductance under dq coordinate system; L _sfor stator winding equivalent self inductance.

Time stator magnetic linkage oriented, ψ _sd=ψ _s, by under double feedback electric engine stator magnetic linkage and mutual inductance calculation of parameter single rotor excitation condition, the specified rate of rotor excitation current component;

i _{rd_ref}＝|ψ _s|/L _m(6)

(3) set-point defining rotor excitation current is the specified rate of Stator energization current component and the specified rate sum of rotor excitation current component, calculate limit lower rotor part electric current d axle component, under Guarantee control system stable case, obtain the given higher limit of rotor excitation current;

Consider that stator winding provides exciting current for setting up magnetic field, the specified rate of definition Stator energization current component is i _{sd_ref}, rotor excitation current the specified rate being given as Stator energization current component and the specified rate sum of rotor excitation current component; Calculate limit lower rotor part electric current d axle component, under Guarantee control system stable case, obtain the given higher limit of rotor excitation current.

$i_{\mathrm{rd}}^{*}=i_{\mathrm{rd}\_\mathrm{ref}}+i_{\mathrm{sd}\_\mathrm{ref}}---\left(7\right)$

Introduce double feedback electric engine stator voltage vector u _swith the angle theta of dq coordinate system d axle _u, for ensureing the stability of system, rotor excitation current givenly to consider its higher limit, avoid approaching restriction and make control system be on the verge of instability area.Limit lower rotor part electric current d axle weight expression:

$i_{\mathrm{rd}}=\frac{L_s}{R_s{L}_m}(\frac{R_s}{L_s}{\mathrm{\ψ}}_s-u_s\cos {\mathrm{\θ}}_u)---\left(8\right)$

If Guarantee control system is stablized, then need therefore can rotor excitation current be obtained given higher limit:

$i_{\mathrm{rd}}^{*}=i_{\mathrm{rd}\_\mathrm{ref}}+i_{\mathrm{sd}\_\mathrm{ref}}\≤2\frac{\left|{\mathrm{\ψ}}_s\right|}{L_m}---\left(9\right)$

(4) picking rate feedback signal, carries out initial torque current observation to double feedback electric engine, calculates initial torque current set-point;

Can be obtained by the electromagnetic torque model of double feedback electric engine in two-phase rotating coordinate system:

$T_{\mathrm{em}}=-\frac{3}{2}{n}_p\frac{L_m}{L_s}{\mathrm{\ψ}}_s\·i_{\mathrm{rq}}---\left(10\right)$

In formula: n _pfor double feedback electric engine number of pole-pairs.

The then torque current component i of double fed electric machine rotor electric current _rqfor:

$i_{\mathrm{rq}}=-\frac{2}{3}\frac{L_s}{n_p{L}_m{\mathrm{\ψ}}_s}\·T_{\mathrm{em}}---\left(11\right)$

When stator magnetic linkage is constant, by regulating double feedback electric engine torque current component i _rq, can independently control its electromagnetic torque, and electromagnetic torque component can be obtained by tach signal double feedback electric engine mechanical equation formula.For this reason, picking rate feedback signal n, carries out initial torque current observation to double feedback electric engine, definition initial torque current i _rq, setting initial moment gain coefficient is η, and speed feedback gain coefficient is k, convolution (11), then initial torque current set-point specifically can be realized by following expression formula:

$i_{\mathrm{rq}}^{*}=k\·n+\∫\mathrm{\η}\·n\·\left|n\right|\mathrm{dt}---\left(12\right)$

(5) realize rotor current closed-loop control based on pi regulator, adopt feedforward compensation strategy, making rotor current inner ring realize uneoupled control, meanwhile, is simple first order inertial loop relation by the Relationship Change of rotor-end voltage and rotor current.

Double-fed motor speed adjusting is the object reaching electromagnetic torque and power control by controlling double fed electric machine rotor terminal voltage vector, for this reason, needs the corresponding relation obtaining rotor-end voltage and rotor current:

$\left\{\begin{array}{c}{u}_{\mathrm{rd}}=R_r{i}_{\mathrm{rd}}+(L_r-\frac{L_m^2}{L_s}){\mathrm{pi}}_{\mathrm{rd}}-{\mathrm{\ω}}_s(L_r-\frac{L_m^2}{L_s})i_{\mathrm{rq}}\\ u_{\mathrm{rq}}=R_r{i}_{\mathrm{rq}}+(L_r-\frac{L_m^2}{L_s}){\mathrm{pi}}_{\mathrm{rq}}+{\mathrm{\ω}}_s(L_r-\frac{L_m^2}{L_s})i_{\mathrm{rd}}+{\mathrm{\ω}}_s\frac{L_m}{L_s}{\mathrm{\ψ}}_{\mathrm{sd}}\end{array}\right.---\left(13\right)$

In formula: ω _sfor d, q reference axis is relative to the angular speed of rotor; u _rd, u _rqthe component of rotor voltage at d, q axle respectively; i _rd, i _rqthe component of rotor current at d, q axle respectively; L _mfor winding equivalence mutual inductance under d, q coordinate system; L _s, L _rbe respectively stator, rotor windings equivalent self inductance.

Closed loop has the ability eliminating disturbance in ring, and adopt pi regulator as the controller of inner ring electric current loop, it exports the control as rotor current dynamic item, and its governing equation is as follows:

$\left\{\begin{array}{c}{u}_{\mathrm{rd}}=(k_p+\frac{k_i}{s})(i_{\mathrm{rd}}^{*}-i_{\mathrm{rd}})-{\mathrm{\ω}}_s(L_r-\frac{L_m^2}{L_s})i_{\mathrm{rq}}\\ u_{\mathrm{rq}}=(k_p+\frac{k_i}{s})(i_{\mathrm{rq}}^{*}-i_{\mathrm{rq}})+{\mathrm{\ω}}_s(L_r-\frac{L_m^2}{L_s})i_{\mathrm{rd}}+{\mathrm{\ω}}_s\frac{L_m}{L_s}{\mathrm{\ψ}}_{\mathrm{sd}}\end{array}\right.---\left(14\right)$

Bring formula (14) into formula (13), the Relationship Change of rotor terminal voltage and rotor current can be obtained for simple first order inertial loop relation is such as formula shown in (15), visible employing feedforward compensation strategy, make double fed electric machine rotor current inner loop achieve uneoupled control, electric current loop has good control characteristic.

$\begin{array}{c}\left[\begin{array}{c}{\mathrm{pi}}_{\mathrm{rd}}\\ {\mathrm{pi}}_{\mathrm{rq}}\end{array}\right]=\left[\begin{array}{cc}-\frac{L_s}{L_s{L}_r-L_m^2}[R_r+(k_p+\frac{k_i}{s})]& 0\\ 0& -\frac{L_s}{L_s{L}_r-L_m^2}[R_r+(k_p+\frac{k_i}{s})]\end{array}\right.\\ +(k_p+\frac{k_i}{s})\left[\begin{array}{c}{i}_{\mathrm{rd}}^{*}\\ i_{\mathrm{rq}}^{*}\end{array}\right]\end{array}\left[\begin{array}{c}{i}_{\mathrm{rd}}\\ i_{\mathrm{rq}}\end{array}\right]---\left(15\right)$

In formula: R _rfor double fed electric machine rotor resistance.

(6) rotor d, q axle control voltage is converted through 2r/2s, obtain the rotor voltage needed for control under two-phase static α β coordinate system, this voltage is supplied to SVPWM module as the reference voltage, adopting Voltage space vector PWM (SVPWM) modulation algorithm to generate trigger impulse drives inverter to be rotor-exciting, indirectly make stator winding carry out stator excitation from electrical network absorption is idle, thus realization carry startup control to the excitation con-trol of double feedback electric engine and zero-speed band.

Adopt the emulation of said method of the present invention and experimental result as Figure 2-3.Emulation and experiment parameter are: double feedback electric engine rated power is 15kW, stator rated voltage 380V, rotor voltage 218V, and stator rated current is 33.5A, and rotor rated current is 46.5A, and DC bus-bar voltage is 600V.As shown in analogous diagram 2, double feedback electric engine carries (T at zero-speed band _l=-50N.m) time, double feedback electric engine rotating speed can be stabilized in zero-speed after instant jitter, and rapidly, Tem=-50N.m during stable state, embodies and control good zero-speed control performance the response of double feedback electric engine electromagnetic torque.Double feedback electric engine zero-speed Startup time, given rotor excitation current is-0.2pu, after rotating speed rises, given rotor excitation current is 0.2pu, as shown in Figure 3, rotor excitation current is when being given as negative, namely stator and rotor current excitation is simultaneously under condition of work, torque current still can respond rapidly, rotor-end voltage waveform is known, little under rotor-end voltage ratio independent rotor excitation current specified criteria under the condition that stator and rotor current excitation works simultaneously, and adopt excitation control method of the present invention, DC bus-bar voltage is steady, demonstrate the feasibility of the inventive method.

Although the present invention is with preferred embodiment openly as above, they are not for limiting the present invention, anyly haveing the knack of this those skilled in the art, without departing from the spirit and scope of the invention, from when making various changes or retouch, but same within protection scope of the present invention.

Claims (5)

1. double feedback electric engine excitation con-trol and a zero-speed starting method, is characterized in that: said method comprising the steps of:

(1) gather threephase stator winding voltage and current signal, determine stator magnetic linkage amplitude and stator magnet chain angle;

(2) by stator magnetic linkage and mutual inductance parameter, the specified rate of single rotor excitation condition lower rotor part current excitation component is calculated:

(3) set-point defining rotor excitation current is the specified rate of Stator energization current component and the specified rate sum of rotor excitation current component, calculate limit lower rotor part electric current d axle component, under Guarantee control system stable case, obtain the given higher limit of rotor excitation current;

(4) picking rate feedback signal, carries out initial torque current observation to double feedback electric engine, calculates initial torque current set-point;

(5) realize rotor current closed-loop control based on pi regulator, adopt feedforward compensation strategy, making rotor current inner ring realize uneoupled control, meanwhile, is simple first order inertial loop relation by the Relationship Change of rotor-end voltage and rotor current;

(6) rotor d, q axle control voltage is converted through 2r/2s, obtain the rotor voltage needed for control under two-phase static α β coordinate system, this voltage is supplied to SVPWM module as the reference voltage, adopting Voltage space vector PWM (SVPWM) modulation algorithm to generate trigger impulse drives inverter to be rotor-exciting, indirectly make stator winding carry out stator excitation from electrical network absorption is idle, thus realization carry startup control to the excitation con-trol of double feedback electric engine and zero-speed band.

2. double feedback electric engine excitation con-trol according to claim 1 and zero-speed starting method, it is characterized in that: step (1) is eliminate the impact of initial value for integral and the DC component adopting pure integrator to bring, adopt three low-pass first order filter cascades to build stator flux observer, its corresponding transfer function is:

。

3. double feedback electric engine excitation con-trol according to claim 1 and zero-speed starting method, is characterized in that: step (3) calculates limit lower rotor part electric current d axle component, introduces double feedback electric engine stator voltage vector u _swith the angle theta of dq coordinate system d axle _u, its computing formula is:

In formula: R _sfor double feedback electric engine stator resistance; ψ _sfor stator magnetic linkage amplitude; L _mfor winding equivalence mutual inductance under dq coordinate system; L _sfor stator winding equivalent self inductance.

4. double feedback electric engine excitation con-trol according to claim 1 and zero-speed starting method, is characterized in that: step (5) detailed process is as follows:

A) corresponding relation of rotor-end voltage and rotor current is determined:

In formula: ω _sfor d, q reference axis is relative to the angular speed of rotor; u _rd, u _rqthe component of rotor voltage at d, q axle respectively; i _rd, i _rqthe component of rotor current at d, q axle respectively; L _mfor winding equivalence mutual inductance under d, q coordinate system; L _s, L _rbe respectively stator, rotor windings equivalent self inductance.

B) adopt pi regulator as the controller of inner ring electric current loop, it exports the control as rotor current dynamic item, and its governing equation is as follows:

C) by the Relationship Change of rotor terminal voltage and rotor current be simple first order inertial loop relation such as formula shown:

D) adopt feedforward compensation strategy, make double fed electric machine rotor current inner loop realize uneoupled control.

5. double feedback electric engine excitation con-trol according to claim 1 and zero-speed starting method, is characterized in that: the method is applicable to current transformer power device electric pressure and DC bus-bar voltage is less than the occasion controlling the rotor voltage that double feedback electric engine startup produces.